Any diet that allows you to restrict calories is going to lead to weight loss. As long as you’re not overeating, then all diets will work.

But one question you need to ask yourself is: “How do I feel being on this diet?” What does it do for your energy levels and your hunger levels? How complicated is it to prepare and eat? Does it taste good or does it feel too restrictive? Are the ingredients easy to find, or does it make shopping for groceries a nightmare of confusion looking for unpronounceable foods that are allegedly “super”?

And there are weaknesses in our modern dieting culture. According to the National Center for Health Statistics, in the U.S. almost 70% of adults are either overweight or obese. And what’s more, according to a Center for Disease Control survey, fewer than a quarter of Americans consume the recommended minimum of five servings of fruit and vegetables each day. Sorry, but Fruit Roll-ups don’t count.

Most overweight people have been on a diet. They’ve probably been on more than one diet. So what happened? Why aren’t we all slim, with so many different diets available to us?

Often, it comes down to dietary complexity.

For millennia, eating was pretty basic. We need to eat to survive, and yet food was often in short supply, so we ate anything we could find (including bugs — gross), preferably stuff that was higher in calories, and we scarfed that stuff down like we were on the way to the electric chair.

And yet now the food supply is ample. We have so much overwhelming and super tasty choice available to us, and to match that we have many diets focused on restricting those choices. Hyperbolic statements sell books: Wheat bloats your belly. Grain melts your brain. Sugar is the same as cocaine. Trans fats are … well, they actually are without redeeming qualities. Take it easy on that stuff.

We used to not have to think about what to eat that much, and now it seems like we’re forced to think about it all the time. And the more complicated dieting becomes, the harder it is to follow.

A 2010 study of 390 people published in Appetite looked at dietary complexity and adherence. The authors concluded that, “Perceived rule complexity was the strongest factor associated with increased risk of quitting the cognitively demanding weight management program.” In other words, the easier a diet was to stick to — the fewer rules it had — the more likely people would be able to stick to it long term and achieve and sustain their weight loss goals.

And it’s not just for people looking to lose some weight. A 2006 report in Clinical Diabetes examined the psychological and social aspects of dietary adherence and came to the same conclusions: fewer rules and fewer restrictions create greater compliance and long-term adherence. A 2005 report published in Therapeutics and Clinical Risk Management said, “In some disease conditions, more than 40% of patients sustain significant risks by misunderstanding, forgetting, or ignoring healthcare advice.” And that includes dietary advice. Too much complexity is often to blame.

And that’s the same conclusion that Jutta Matta and her research team at the Max Planck Institute for Human Development came to in a 2007 article published in Appetite. The authors looked at over 1,200 participants who had been on a variety of diets. They examined diets that had “excessive cognitive demands” and found that: “diets with more complex diet rules correlate with lower adherence rates from clinical trials examining popular weight loss diets.” The authors also stated that: “perceived difficulty reported at the first measurement point predicts quitting of the diet prematurely (i.e., before goal weight or time planned to be on diet are reached) at later points in time.”

The Cost Of Complexity
The problem with overly complex diets is that they suck the fun out of life. If you’re always on guard about gluten (and not celiac), wary of wheat, seeing sugar as sinful, dissing dairy or maligning meat, it creates a mental state that is fearful of food and can lead to an eating disorder. As my friend and registered dietitian Jennifer Sygo says, “The science of nutrition is complex. Eating shouldn’t be.”

Because if you make it too complex, you’re less likely to stick to the diet long-term, which results in going off the diet and often rebounding with overeating and gaining back all the weight you lost. Sometimes it’s a diet that is too complex, or sometimes it’s based on a gimmick, or sometimes it’s both.